The metabolism and kinetics model of Fernandez modified by Lopes et al. (2001) is a fundamental tool for the study of the digestive physiology of phosphorus (P) in pigs. In Brazil there is a great potential of use of rock phosphate and those represents approximately 2.9 billion metric tons. Brazilian researchers are interested to evaluate those phosphate as alternative sources in diets of pigs. All of the natural sources of phosphate in Brazil presented low level of fluor, when compared with international sources and levels of heavy metals are considered low too. The main concern resides in the fact that non-absorbed P is excreted and can cause contamination of water. The purpose of this research was to evaluate the digestive physiology of pigs fed diets supplemented with different P sources and the study the environmental pollution provoked by P excreted.